Police arrested nearly two dozen anti-Wall Street protesters in US cities over the weekend, while tensions mounted elsewhere as local officials stepped up pressure for demonstrators to abandon their encampments.

In Portland, Oregon, protesters and their supporters flooded a city park area yesterday in defiance of an eviction order, and authorities elsewhere stepped up pressure against demonstrators, arresting nearly two dozen.

Organisers said they hoped enough people would join them to make it difficult if not impossible for police to carry out evictions.

"Occupy the street," one organiser said through a megaphone. "Remain peaceful and aware. We have strength in holding the streets."

The eviction notice come as officials across the country urged an end to similar gatherings in the wake of three deaths in different cities, including two by gunfire.

The Occupy Wall Street movement began in New York's financial district in September, saying it was acting against corporate greed and economic inequality. Similar protests have followed in dozens of major cities and hundreds of smaller communities under the Occupy banner. AP